The manufacture of composite insulated glass assemblies by applying a spacer between spaced glass substrates at the periphery of the substrates is well known. The majority of commercially available spacers comprise a rigid metal structure, which may also incorporate an insulating polymeric layer. Increasingly, spacers fabricated entirely of resilient flexible polymeric material are used for their improved insulating and sealing abilities. However, after application of the spacer, there may be a peripherally extending gap. A major problem can occur at corners and/or at the joints between the adjacent ends of the spacer, and in fact at any position where the cross section of the spacer is reduced. This problem has been addressed in the past by costly and labor-intensive solutions. For example, metal composite spacers typically feature a butt joint at each corner at the intersection between adjacent spacers. The abutting spacers are joined by means of an insert or a mating structure. This arrangement is subject to eventual leakage as the window shifts, and is labor-intensive to assemble. In a resilient flexible spacer, to provide for a relatively sharp corner at the window corners, the spacer can form separate lengths that join at one or more corners. Alternatively, the spacer may be cut partway through to permit the spacer to describe a sharp bend.
As is well known, any discontinuity in the spacer creates significant energy losses and results in a weak spot through which moisture can leak. Previously, it has been proposed that taping be used or alternatively simply applying a filler material which is not bonded to the spacer.
A further limitation of the prior art resides in the position of the spacer relative to the periphery of the glass substrates. Conventional polymeric spacers comprise a generally unitary body and it is difficult to maintain a gas impermeable seal between the spacer and the glass substrates. Conventionally, the seal is improved by maintaining a space between the periphery of the spacer and the periphery of the glass substrates, and applying a substantially impermeable backspace material within this gap, about the entire periphery of the assembly. Accordingly, it is desirable to provide a method for fabricating an assembly with a flexible polymeric, insulating spacer that eliminates the need to backfill the entire periphery of the glass assembly. This may be accomplished if the spacer includes an at least partial discontinuity at the corners, thus permitting a relatively sharp bend of the spacer and positioning of the spacer substantially adjacent to the periphery of the glass substrates. The discontinuity may be introduced if specific steps are taken to ensure that the thermal integrity of the spacer is not compromised at the discontinuity. As well, an improved spacer may be used in an assembly, wherein the spacer incorporates a substantially gas-impermeable vapour barrier membrane and is characterized by an improved seal. The use of such a spacer, permits the spacer to be positioned substantially adjacent to the periphery of the glass thus substantially eliminating the need to backfill about the entire periphery of the assembly.